Inorganic peroxygen compounds, in particular hydrogen peroxide and solid peroxygen compounds that dissolve in water with release of hydrogen peroxide, such as sodium perborate and sodium carbonate perhydrate, have been used for some time as oxidizing agents for disinfection and bleaching purposes. The oxidizing effect of these substances in dilute solutions depends greatly on temperature; thus, sufficiently rapid bleaching of stained textiles in alkaline bleaching baths is achieved, for example, with H2O2 or perborate only at temperatures above about 80° C. At lower temperatures, the oxidizing effect of the inorganic peroxygen compounds can be improved by the addition of so-called bleach activators, which are capable of affording peroxocarboxylic acids under the above-discussed perhydrolysis conditions and have become known in the literature for numerous proposals, chiefly from the substance classes of N- or O-acyl compounds, for example, reactive esters, polyacylated alkylenediamines, in particular N,N,N′,N′-tetraacetylethylenediamine (TAED), acylated glycourils, in particular tetraacetylglycouril, N-acylated hydantoins, hydrazides, triazoles, hydrotriazines, urazoles, diketopiperazines, sulfurylamides, and cyanurates, also carboxylic acid anhydrides, in particular phthalic anhydride, carboxylic acid esters, in particular sodium nonanoyloxybenzenesulfonate (NOBS), sodium isononanoyloxybenzenesulfonate, O-acylated sugar derivatives such as pentaacetyl glucose, and N-acylated lactams, such as N-benzoylcaprolactam. The addition of these substances can increase the bleaching effect of aqueous peroxide baths so far that substantially the same effects that already occur at temperatures of around 60° C. occur as with the peroxide bath alone at 95° C.
In efforts to achieve energy-saving washing and bleaching methods, utilization temperatures still appreciably below 60° C., in particular below 45° C., down to cold water temperature have also become important in recent years.
The action of hitherto known activator compounds normally decreases perceptibly at these low temperatures. There has therefore been no lack of effort to develop more effective activators for this temperature range. The use of transition metal compounds, in particular transition metal complexes, to boost the oxidizing power of peroxygen compounds or also of atmospheric oxygen in washing and cleaning agents has also been proposed on various occasions. Transition metal compounds proposed for this purpose include, for example, salen complexes of manganese, iron, cobalt, ruthenium, or molybdenum, carbonyl complexes of manganese, iron, cobalt, ruthenium, or molybdenum, complexes of manganese, iron, cobalt, ruthenium, molybdenum, titanium, vanadium, and copper with nitrogen-containing tripod ligands, and manganese complexes with polyazacycloalkane ligands, such as TACN. A disadvantage of such metal complexes, however, is either that they possess in part a bleaching power that is insufficient especially at a lower temperature, or, if they have sufficient bleaching power, that undesired damage can occur to the colors of the material that is to be washed or cleaned, and if applicable even to the material itself, for example, the textile fibers.
It is known from the international patent application WO 2013/017476 A1 that bleaching-active species that have a bleach-intensifying effect can be generated from sterically hindered N-hydroxy compounds such as, for example, 1-hydroxy-2,2,6,6-tetramethylpiperidine by electrolysis.
It has now been found surprisingly that the action of such mediator compounds can be increased still further if they carry an anionic substituent.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.